Mouse CD8(+) CD122(+) T cells with intermediate TCR increasing with age provide a source of early IFN-gamma production

Although CD8(+) IL-2R beta (CD122)(+) T cells with intermediate TCR reporte dly develop extrathymically, their functions still remain largely unknown. In the present study, we characterized the function of CD8(+) CD122(+) T ce lls with intermediate TCR of C57BL/6 mice. The proportion of CD8(+) CD122() T cells in splenocytes gradually increased with age, whereas CD8(+) IL-2R beta-negative or -low (CD122(-)) T cells conversely decreased. The IFN-gam ma production from splenocytes stimulated with immobilized anti-CD3 Ab in v itro increased with age, whereas the IL-4 production decreased. When sorted CD8(+) CD122(+) T cells were stimulated in vitro by the anti-CD3 Ab, they promptly produced a much larger amount of IFN-gamma than did CD8(+) CD122(- ) T cells or CD4(+) T cells, whereas only CD4(+) T cells produced IL-4. The depletion of CD8(+) CD122(+) T cells from whole splenocytes greatly decrea sed the CD3-stimulated IFN-gamma production and increased the IL-4 producti on, whereas the addition of sorted CD8(+) CD122(+) T cells to CD8(+) CD122( +) T cell-depleted splenocytes restored the IFN-gamma production and partia lly decreased IL-4 production. It is of interest that CD8(+) CD122(+) T cel ls stimulated CD4(+) T cells to produce IFN-gamma, The CD3-stimulated IFN-g amma production from each T cell subset was augmented by macrophages. Furth ermore, CD3-stimulated CD8(+) CD122(+) T cells produced an even greater amo unt of IFN-gamma than did liver NK1.1(+) T cells and also showed antitumor cytotoxicity. These results show that CD8(+) CD122(+) T cells may thus be a n important source of early IFN-gamma production and are suggested to be in volved in the immunological changes with aging.